1. Field of the Invention
This invention concerns an ignition system for internal combustion engines, in general. More specifically, it deals with a particular type of ignition system which employs a high-frequency continuous-wave oscillator to supply a controlled-duration spark signal.
2. Description of the Prior Art
A high-frequency continuous-wave ignition system has been developed which is particularly well adapted to provide a controlled spark-duration signal. However, in the case where it was desired to provide for a step change in the timing of the spark signals, relative to the engine rotation, it was found necessary to employ a pair of sensors that were fixed relative to the crank angle of the engine. The arrangement was such that one or the other sensor would generate the timing signals to control the ignition spark outputs. Such arrangement is shown in a U.S. Pat. No. 4,022,177 issued May 10, 1977. The above noted application discloses a system that is applicable to the same type of ignition signal, and it can produce a controlled-duration AC spark signal that will last for an interval that covers a particular amount of crank angle degrees irrespective of the speed of operation of the engine.
On the other hand, this invention provides a system such that only a single sensor need be employed to initiate the spark timing. And, a predetermined step change in such timing may be chosen at will, which step will maintain a given crank angle timing position irrespective of the speed of the crank shaft.